Type carrier for high speed printing mechanism



P 1965 F. H. SCHALLER 3,207,067

TYPE CARRIER FOR HIGH SPEED PRINTING MECHANISM Filed Aug. 21. 1962 2 Sheets-Sheet 1 INVENTOR. FRANK H. SCHALLER ATTORNEY BY MMM' Sept. 21, 1965 F. H. SCHALLER 3,207,067

TYPE CARRIER FOR HIGH SPEED PRINTING MECHANISM Filed Au 21, 1962 2 Sheets-Sheet 2 FIG. 6

INVENTOR. FRANK H. SCHALLER Mmw ATTORNEY United States Patent 3,207,067 TYPE CARRIER FOR HIGH SPEED PRINTING MECHANISM Frank H. Schaller, Westport, Conn., assignor to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Filed Aug. 21, 1962, Ser. No. 218,257 15 Claims. (Cl. 101-93) This invention relates generally to high speed printing devices and, more particularly, to printing devices wherein the type font is arranged on a continuously rotating carrier and printing is achieved on the fly on a print receiving medium disposed between the carrier and type hammers which are driven to impact the print receiving medium along with a suitable transfer medium against the carrier at a selected interval during the carriers rotation.

In printing devices operating on the above-mentioned principles, it will be readily apparent that print density of the printed image for a given hammer mass, hammer velocity and paper-ribbon-carbon pack is determined primarily by the nature of the type face, and that for type faces which are identical with respect to the material from which they are formed, depth (relief above base structure) and support, the print density is determined by the relative area of the type face. It will therefore be evident that for a font of type which is similarly formed and supported, the type with relatively small face areas will print relatively dark up to the limit of paper puncture and the type with relatively large face areas will print relatively light up to the point where the ink or carbon is not adequately transferred. From the foregoing, it will be readily apparent that for the printing of characters having a range of varying face areas, the narrower the range between the type having the least face area and that having the greatest face area, the lesser will be the variation in the density of the corresponding printed images.

In printing devices of this class it will also be understood that, depending upon the speed of rotation of the type carrier, a certain amount of smearing of the printed image will occur. The amount of smearing varies directly with the extent of contact time of the print hammer, said time being herein defined as the duration between the moment of impact and the moment of rebound of the hammer from the type carrier. It has been found that the contact tie varies from one character to another in accordance with the face area of the type, the relationship being that type with relatively larger face area produces relativley lesser contact time while type with a relatively small face area produces a relatively greater contact time. Accordingly, for these reasons also it is desirable that the range of face areas of all of the type in the type font be minimized in order that the extent of smear in the printed image be more uniform thereby producing a more even line of printed characters.

From the foregoing, it will be apparent that attainment of maximum uniformity in image density could be achieved by fashioning the type faces in such a manner that they all would have equal type face area. However, such a solution, as far as the characters employed in the English alphabet and the Arabic numeral system, would not be feasible since this would require variations in character stroke width from a nominal stroke width which 3,207,067 Patented Sept. 21, 1965 in many instances would result in the character imprint showing a range of boldness which would be objection-able for most business use.

According to the invention, the range of face area of the several type is narrowed by reducing the stroke width of the characters nominally having the greater face area and by widening or increasing the stroke width of the characters nominally having the lesser face area. In addition, since smearing of the printed image always extends parallel to the direction of type carrier rotation, the strokes of each character which are oriented perpendicularly to the direction of type carrier rotation are fashioned thinner than the strokes which are parallel to the direction of type wheel rotation to thereby compensate for the amount of smearing and provide the perpendicularly oriented strokes of the printed character with the same width or boldness as the parallel strokes.

In fashioning the type in this manner there may still remain a range of face areas due to the limitations imposed by the arbitrarily selected nominal stroke width, and even if an optimum compromise has been made with respect to density and boldness, the resulting non-uniformity in face areas will cause the height of the printed image to be non-uniform, in the case of vertically moving type, as a result of varying degrees of smearing, and this will appear as print misalignment. It has been determined empirically that most observers judge print alignment by noticing the alignment of the bottom edges of characters in a line of printing rather than noticing the height uniformity of characters in the line. For this reason a compromise solution which results in aligning the bases of the printed characters is usually acceptable. This is accomplished by locating characters in slightly oifset relation to an extent corresponding to the amount of smear and in such a manner that the printed characters containing the greater smear will be slightly higher than the characters containing lesser smear, but the bases of all printed characters will extend in correct alignment with each other. This, of course, assumes that the height of each type face is uniform. If it were necessary in certain applications to maintain the height of all printed characters absolutely uniform, this can also be obtained by fashioning the type faces in the same manner as heretofore described with the further condition that the height of the type faces be non-uniform, depending upon their face area, so that the sum of non-uniform type face height and non-uniform smear will result in uniform printed image height for all characters.

It is therefore an object of this invention to achieve substantial uniformity of density in the character imprint of a high speed impact form of printer.

It is a further object of this invention to achieve substantial uniformity in the boldness and density of the character imprint produced by a high speed impact form of printing mechanism.

It is still further object of the invention to improve the alignment of character imprint produced by a high speed impact form of printing mechanism.

Further objects of the invention together with the features contributing thereto and the advantages accruing therefrom will be apparent from the following description when read in conjunction with the drawing wherein:

FIG. 1 is a sectional View in side elevation of a high speed printing mechanism of the sort to which the invention relates.

FIG. 2 is a fragmentary view in enlarged scale of a portion of the type drum of FIG. 1.

FIG. 3 is an enlarged view illustrating separately the initial and smear imprint made by one of the character type formed on the surface of the type drum.

FIG. 4 is an enlarged fragmentary view of a section of the type drum illustrating variations in the alignment of different character type faces with their respective timing reference points.

FIG. 5 is a view similar to FIG. 4 illustrating the variation in height of the character type faces.

FIGS. 6 through 9 are each compositive views of different character type faces arranged along side the character imprint produced thereby to illustrate the extent of each imprint which results from the smearing action of the constantly rotating type drum.

With reference now to FIG. 1, the mechanism by which printing is effected includes a type carrier in the form of a drum 10 suitably keyed to a continuously rotating shaft 11, the shaft rotating in a counter-clockwise direction in the present instance so as to serially advance type faces 20 (see FIG. 2), arranged columnarly around the periphery of the drum, into registration with a type hammer 12. The print receiving medium 13, which may be paper or other suitable material, is disposed between the head of the print hammer and the type drum, the said medium being supported and fed in line spacing direction by any suitable means such as sprocket wheel 14. Disposed between the print receiving medium and the type drum is a marking transfer medium in web or roll form, which may be impregnated either with ink, carbon, or the like, for transferring the image of each character type face to the surface of the print receiving medium when the type hammer 12 is actuated to impact the print receiving medium 13 and marking transfer web 15 against the surface of a selected character type face on the type drum 10. The marking transfer medium 15 is drawn around guide rolls 16 by any suitable feeding mechanism, not shown, and is maintained out of contact with the print drum, except at the print registration area, by arcuate shields 17 mounted in close proximity to the drums surface on each side of the print registration area.

The type hammers 12 are driven at selected intervals in a cycle of drum rotation by electromagnetic actuators each of which includes a coil 21 and a pivotally mounted armature 22 which has one arm engaging the shank of the type hammer and thereby causing the print hammer to fire into impacting relation with a selected type face 20 on the drum at the moment that the electromagnetic coil 21 is energized. This action causes the image of the selected character type face to be transferred through the marking medium 15 and reproduced on the print receiving medium 13. It will, of course, be understood that although a single sheet print receiving medium is shown in FIG. 1, this medium could comprise several sheets bound with interleaved marking transfer means, such as carbon paper or the like, in the event that the plural copies of the print receiving medium were desired.

As best seen in FIG. .2, the character type faces 20 are arranged about the periphery of the type drum 10 in a series of rows and columns with each column, which runs perpendicularly to the axis of the drum, containing a full complement of type faces including one for each letter of the alphabet, each numeral in addition to each commonly used punctuation mark. The several columns of type faces are arranged in the present instance, but which arrangement is not essential to the inventive concept herein disclosed, in alternately offset relationship in a checkboard array with the result that each character occupies two adjacent rows extending in a direction parallel to the drum axis. Associated with each row of character type faces 20 is a raised bar-like structure 23 formed on the drum surface which is utilized, when setting up the mechanism, for registering'each row of type faces with the type hammer firing time control means,

lnot shown herein since it is not deemed necessary for an understanding of the instant invention, which bar structure 23 may be considered as providing a timing control reference point for its associated row of character type faces.

It will, of course, be understood that, in printing mechanisms of this sort, when the type hammer is fired the initial impact thereof against a selected type face 20 on the type drum wilf cause a transfer of the exact image onto the print receiving medium, and as long as the print receiving medium together with the marking transfer medium are held in contact with the surface of the type face, hereinafter referred to as contact time, with the type drum constantly rotating, the resulting image transferred to the print receiving medium will contain a smear which distorts or tends to elongate the exact configuration of the type face in the direction of drum rotation. The extent of the smearing effect is dependent upon the length of contact time in relation to the speed of type drum rotation.

FIG. 3 shows the imprint for the character H in enlarged scale indicating that portion of the imprint formed by the initial impact of the type hammer separately from that portion of the imprint caused by the smearing action by the rotating type face during the contact time of the type hammer against the type face. For purposes of explanation, the character imprint may be considered as being composed of strokes which in the case of the character H consist of two vertical strokes 31i, 321' connected by a horizontal stroke 331'. The stippled areas 31s, 32s constitute the smear produced by the vertical strokes of the character type face during contact time while the stippled area 33s represents the smear produced by the horizontal stroke of the type face during contact time. It will be noted that in the case of horizontal stroke 331', the effect of the smearing on the print receiving medium 13 is to increase the width or boldness of the horizontal stroke, and for this reason the horizontal stroke of the corresponding character type face is formed of a lesser width than that of the vertical strokes which in the reproduced image will not appear wider from the smear action but will lengthen as a result of the smear action. Accordingly, by fashioning the type face so that the horizontal stroke of the character is of lesser width than the vertical strokes, the resulting reproduced image of the character will appear with all strokes, whether horizontal or vertical, of substantially identical width or boldness.

FIGS. 6 through 9 illustrate the configuration of several other character type faces 20 in relation to the resulting image reproduced therefrom. In the case of the character E, shown in FIG. 6, the type face consists of a vertical stroke 41 and horizontal strokes 42, 43, 44 which reproduce an image consisting of the exact replica of the character type face, comprising the vertical stroke area 411' and horizontal areas 421', 43i, 44i, in addition to the imprint smear areas 42s, 43s, 44s. By fashioning the horizontal strokes of the type face for the character E with reduced thickness from that of the vertical stroke it will be apparent that the reproduced image will appear with all strokes, both vertical and horizontal, of the same thickness or boldness.

In the case of the numerical character 1, shown in FIG. 7, the character type face is comprised of a vertical stroke 45, horizontal stroke 46 and a diagonal stroke 47. In this case both the horizontal stroke 46 and the diagonal stroke 47 are fashioned of reduced thickness from that of the vertical stroke 45 so that in the reproduced image the smeared areas 47s and 46s provide the diagonal and horizontal strokes with the same thickness or boldness as the vertical stroke 45i.

In the case of the numerical character 5, shown in FIG. 8, the type face consists of a horizontal stroke 51, a vertical stroke 52 and a curvilinear stroke 53. In this case the horizontal stroke 51 is similarly fashioned of reduced thickness from that of the vertical stroke 52 so that in the resulting image this stroke, including the smear area 51s, will appear with the same boldness as the vertical stroke image 521. The curvilinear stroke 53 of the character 5 type face, since it includes both horizontal and vertical segments, is fashioned with the horizontal segment thereof reduced in thickness from the vertical segment thereof so that in the resulting reproduced image the entire stroke including the smear areas 53s will appear with uniform thickness which also cor-responds to the thickness of the vertical stroke 521.

In the case of the numerical character 9, shown in FIG. 9, the character type face is comprised of curvilinear strokes 55, 56. Thus, similarly to the curvilinear stroke of the numerical character 5 just described, these strokes are fashioned to render the horizontal segments thereof reduced in thickness from that of the vertical segments, with the strokes graduated in thickness between the horizontal and vertical segments, so that in the reproduced image, comprised of identical imprint areas 551, 561' and smear imprint areas 55s, 56s, all segments of the curvilinear strokes comprising the image of the character 9 will appear with uniform thickness or boldness.

In a similar manner all of the other character type faces are fashioned according to the same principle with the horizontal strokes or horizontal segments of curvilinear strokes formed with reduced thickness relative to the vertical strokes or vertical segments of curvilinear strokes so that in each case the resulting reproduced image will appear in uniform boldness. The above explanation is, of course, predicated on the presumption that it is desired that all strokes of the reproduced image appear in uniform boldness. In the event that it is desired to stylize the character type faces to reproduce images in which all strokes of a character would not appear with uniform boldness it Will, of course, be understood that corresponding modifications of the type faces could be accomplished to produce this result while still, however, fashioning the type face so as to compensate for the more pronounced effect of the smearing action in the horizontal strokes of a character image than in the vert-ical strokes.

From the foregoing it will be apparent that a result of the smearing action is to render each reproduced image with a greater height than the corresponding character type face since, in the disclosed embodiment of printing mechanism, the type faces are traveling in a vertical plane. Furthermore, since the type faces are traveling downwardly relative to the print receiving medium, the smear portion of the reproduced image will always appear along the bottom edge of the character imprint. If the extent of smear were uniform for all characters there would be no serious problems resulting from the smearing action with respect to print alignment or uniformity in the height of character imprint. However, it has been found that the extent of smear is not uniform for all characters and varies from one character to another since the contact time is not uniform from one character to another. The contact time is dependent upon the face area of the character type face, with the characters possessing the lesser type face area having a longer contact time and consequently producing a greater extent of smear than the characters having a greater type face area. Accordingly, variations in character height will appear along the bottom edge of the character imprints, which is the line of sight by which a line of characters is most effectively judged for character alignment. In order to compensate for the variations in the extent of smear from one character to another so as to produce a line of character imprints having their bottom edges in correct alignment, various rows of character type faces may be arranged on the type drum 10 in slightly offset relation to their timing reference points so that the bottom edges of all character imprints will appear on the print receiving medium in correct lateral alignment. This offset disposition of various rows of character type faces can be seen by reference to FIG. 4. As heretofore mentioned, the bars 23 on the face of the type drum 10 are timing reference points for their associated row of character type faces, said bars being disposed in uniformly spaced-apart relation around the periphery of the type drum. FIG. 4 is marked to indicate the height, h, of the character type faces which in this instance is uniform for all characters on the type drum and in the present disclosed embodiment amounts to one hundred thousandths of an inch for all characters shown. FIG. 4 is also marked to show the lead distance, I, from the bottom edge of the character type face to the center line of the timing reference bars 23 associated therewith. Of the three different character type faces shown in FIG. 4,the type face for character C has the least face area, and that of character A has a face area between that of character C and character B. Accordingly, the lead distance, I, for character C is slightly less than that for character A which in turn is slightly less than that for character B since, as heretofore mentioned, the amount of smear produced by the character C type face will be slightly greater than that for character A which in turn will be slightly greater than that for character B. Thus by varying the lead distance, 1, between the bottom edge of a character type face and the associated timing reference point in accordance with type face area all character imprints will appear in lateral alignment on the print receiving medium. Obviously, the same result can alternatively be attained by maintaining uniformity in the spacing of successive rows of type faces and offsetting the timing reference bars 23 relative thereto so as to provide the appropriate lead distance, I, for each row.

As heretofore mentioned, variations in'the amount of smear produced by the different type faces, depending upon the total area of the type face, will produce corresponding variations in the height of the printed image. However, as long as the bottom edge of the character imprints are maintained in lateral alignment, the variation in type imprint has not been found to be objectionable for most business use. If it were desired, nevertheless, to achieve uniform height of the printed images, regardless of the extent of smear in the reproduced image, this may also be achieved by appropriately fashioning the respective type faces in different heights to compensate for the variation in smear in the reproduced image. As shown in FIG. 5, the height, h, of the type face for the character L is slightly less than that of the type face for the character M. Since the former has a lesser face area than the latter, the image reproduced from the character L type face will appear uniform in height with that of the image produced by the character M type face. As is also shown in FIG. 5, the lead distance, I, for the character L type face from its associated timing reference point 23 is slightly less than that for the character M, for reasons heretofore explained, so that the images produced by the L and M type faces will not only be in horizontal alignment along their bottom edge but will also be of uniform height.

It will, of course, be understood that reference herein to varying height of character imprint and smear in a vertical direction, etc., pertain to the specific embodiment of printing mechanisms herein disclosed in which the type faces are in constant motion in a vertical plane perpendicular to the line of print. If the type wheel were otherwise oriented relative to the line of print such as to move the type faces, for example, horizontally and parallel to the print line, the same inventive concepts could equally well be emplyoed to achieve uniformity and, in which case, the smear effect would extend in a horizontal rather than a vertical direction.

It will also be understood that in achieving uniform boldness between the strokes of agiven character image, the extent to which horizontal type face strokes are reduced in boldness from the vertical strokes will vary in accordance with total type face area, since the extent of smearing is greater in the case of type faces of lesser face area. However, as heretofore mentioned, the range of type face areas among the several characters is preferably reduced in order to achieve more uniform density of the printed image, since if all character type faces were formed to print in equal boldness the wide variation in type face areas would produce a correspondingly wide variation in the print density of the various characters. For these reasons the type faces having lesser face area are fashioned bolder than the type faces having greater face area, and this can be seen by reference to FIGS. 6 and 7 wherein the width, w, of the vertical stroke 45 for the numerical character 1 is greater than the width, w, of the vertical stroke 41 for the character E, since numerical character 1 has lesser face area than character E. By thus compensating for variations in character type face area, the density of the resulting printed images will be rendered more uniform.

While there have been shown and described what are considered to be preferred embodiments of the invention, it will, of course, be understood that variations in form could be made without departing from the spirit of the invention, and it is therefore intended that the invention be not limited to the exact forms herein shown and described nor to anything less than the whole of the invention as hereinbefore set forth and as hereinafter claimed.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A type carrier adapted for continuous rotation in an impact on the fly form of high speed printing mechanism having type hammer means and actuator means for impelling said hammer means to impact a print receiving medium and a marking transfer medium against the rotating periphery of said carrier, the surface of said carrier being formed with raised type faces for a plurality of characters having a corresponding variety of type face areas, said type faces being arranged in rows and columns with each row containing type faces for the same character, means defining a row firing time reference point associated with each of said rows for registering its respective row of type faces with said actuator means, each of said rows being relatively offset in a columnwise direction from a row firing time reference point to an extent corresponding to the type face area of a type face in the respective row, whereby the smear produced in the resulting character image imprint results in placing one edge of all character imprints of a printed line in alignment.

2. The invention according to claim 1 wherein the type faces having the lesser amount of face area are relatively offset the greater extent.

3. The invention according to claim 1 wherein said type faces are rotated within a plane perpendicular to the print line, whereby the bottom edge of all character imprints in the print line are in alignment.

4. The invention according to claim 1 wherein the height of the type faces for different characters varies in accordance with the face area of the respective type faces, whereby the resulting character images are uniform in height for all characters.

5. The invention according to claim 4 wherein the variation in height of the type faces for the several characters varies in direct ratio to their variation in type face area.,

6. The invention according to claim 1 wherein the type faces define a configuration of line strokes variously oriented relative to the direction of type face motion, the strokes perpendicularly oriented being fashioned in reduced width from those oriented parallel to said direction of motion to thereby produce a print image in which the corresponding line strokes are more nearly uniform in width.

7. The invention according to claim 6 wherein the diagonally oriented strokes of a character type face are reduced in width from the strokes oriented parallel to the direction of type face motion.

8. The invention according to claim 1 wherein a type face defines a configuration of line strokes variously oriented relative to the direction of type face motion and including a curvilinear stroke, the segments of said curvilinear stroke oriented perpendicularly to the direction of type face motion being reduced in thickness from the segments oriented parallel to the direction of type face motion, whereby the entire curvilinear stroke of the resulting character image appears uniform in width.

9. The invention according to claim 8 wherein the portion of a curvilinear stroke interconnecting a perpendicularly oriented segment with a parallel oriented segment thereof is graduated in width in accordance with the extent of deviation thereof from a plane parallel to said direction of type face motion.

10. A type carrier adapted for continuous rotation in an impact on the fly form of high speed printing mechanism having type hammer means and actuator means for impelling said hammer means to impact a print receiving medium and marking transfer medium against the rotating periphery of said carrier, the surface of said carrier being formed with raised type faces for a plurality of characters having a corresponding variety of type face areas, said type faces being arranged in rows and columns with each row containing type faces for the same character, means defining a row firing time reference point associated with each of said rows for registering its respective row of type faces with said actuator means, each of said rows being relatively offset in a columnwise direction from a row firing time reference point to an extent corresponding to the type face area of a type face in the respective row, each of said type faces defining a configuration of line strokes variously oriented relative to the direction of type face motion, said strokes being fashioned in varying widths in inverse relation to the extent that the stroke deviates from a plane parallel to the direction of type face motion, whereby all strokes of the corresponding character image imprinted on said print receiving medium appear uniform in width.

11. The invention according to claim 10 wherein said type hammer means are disposed along a common plane, and said type carrier comprises a drum rotating about an axis substantially parallel to the plane of said type hammer means.

12. A type carrier adapted for continuous rotation in an impact on the fly form of high speed printing mechanism having type hammer means and actuator means for impelling said hammer means to impact a print receiving medium and a marking medium against the rotating periphery of said carrier, the surface of said carrier being formed with raised type faces for a plurality of characters having a corresponding variety of type face areas, said type faces being fashioned to present a configuration of line strokes for reproduction on said print recording medium by the impact force of said ham mer means, the line strokes for the several characters varying in width in inverse ratio to the respective type face areas of the several characters, whereby the reproduced images of the several characters will appear more uniform in density.

13. The invention according to claim 12 wherein each line stroke configuration of a type face comprises strokes variously oriented relative to the direction of type face motion, the strokes perpendicularly oriented being fashioned in reduced width from those oriented parallel to said direction of motion to thereby produce a printed image in which the corresponding line strokes are more nearly uniform in width.

14. The invention according to claim 13 wherein the extent of width differential between the variously oriented strokes of a type face is dependent upon the area of the type face in relation to the area of the other type faces on said carrier.

15. The invention according to claim 14 wherein said Width differential is greater in a type face having a lesser relative type face area.

References Cited by the Examiner UNITED STATES PATENTS Rookyard 101-212 Hartley 10193 Ayres 19717 Shepard 10193 Wasserman 10193 Squires.

ROBERT E. PULFREY, Primary Examiner.

10 WILLIAM B. PENN, Examiner. 

1. A TYPE CARRIER ADAPTED FOR CONTINUOUS ROTATION IN AN IMPACT ON THE FLY FORM OF HIGH SPEED PRINTING MECHANISM HAVING TYPE HAMMER MEANS AND ACTUATOR MEANS FOR IMPELLING SAID HAMMER MEANS TO IMPACT A PRINT RECEIVING MEDIUM AND A MARKING TRANSFER MEDIUM AGAINST THE ROTATING PERIPHERY OF SAID CARRIER, THE SURFACE OF SAID CARRIER BEING FORMED WITH RAISED TYPE FACES FOR A PLURALITY OF CHARACTERS HAVING A CORRESPONDING VARIETY OF TYPE FACE AREAS, SAID TYPE FACES BEING ARRANGED IN ROWS AND COLUMNS WITH EACH ROW CONTAINING TYPE FACES FOR THE SAME CHARACTER, MEANS DEFINING A ROW FIRING TIME REFERENCE POINT ASSOCIATED WITH EACH OF SAID ROWS FOR REGISTERING ITS RESPECTIVE ROW OF TYPE FACES WITH SAID ACTUATOR MEANS, EACH OF SAID ROWS BEING RELATIVELY OFFSET IN A COLUMNWISE DIRECTION FROM A ROW FIRING TIME REFERENCE POINT TO AN EXTENT CORRESPONDING TO THE TYPE FACE AREA OF A TYPE FACE IN THE RESPECTIVE ROW, WHEREBY THE SMEAR PRODUCED IN THE RESULTING CHARACTER IMAGE IMPRINT RESULTS IN PLACING ONE EDGE OF ALL CHARACTER IMPRINTS OF A PRINTED LINE IN ALIGNMENT. 